Federal snow-monitoring stations in Arizona’s high country recorded not a single flake in January, a striking rarity even in this drought-stricken region. The lack of moisture threatens to stoke a monster wildfire season and ratchet up tensions among states already wary of a declining Colorado River.

Arizona won’t go dry this year, but water managers are getting anxious about the future.

Last week, the Colorado Basin River Forecast Center in Salt Lake City reported that Arizona’s watersheds received less than half of their normal January precipitation — and most of the river basins got just 2 or 3 percent of normal.

Northern Arizona’s lack of January snowfall was the worst in decades and the latest in a string of dry spells that will hurt the state’s water supplies if they keep coming.

Since the turn of the 21st century, the Southwest has been in its most intense dry spell in 400 years, according to tree-ring analysis. Precipitation in some winters during that stretch has rebounded enough to replenish reservoirs and temporarily ease fears, but Lake Powell has been on a downward trajectory that will cause its managers to slow releases to Lake Mead this year.

If conditions remain dry, Lake Mead’s output could fall short of claims to it in 2016, and Arizona would lose part of the 1.5 million acre-feet of Colorado River water that is siphoned off by the Central Arizona Project.

An acre-foot is enough water to supply about two households for a year, though much of it is used for agricultural, not residential, needs.

In addition, two critical forested river basins — the Salt and the Verde — are drying out after a fall deluge had raised hopes for a wet winter. Both basins are at least 40 percent below the norm for precipitation in the water year that started Oct. 1.

The Little Colorado River is dry at Cameron in northern Arizona — something that happens often in fall, but not in February.

“That’s pretty sad,” said Greg Smith, a hydrologist for the Colorado Basin River Forecast Center who singled out the paltry 0.1 inch of precipitation the river got during January. That’s 2 percent of its normal January precipitation. The Little Colorado starts in the White Mountains and flows across the Navajo Reservation to the Grand Canyon.

Across the West

The same dry conditions that have gripped California — the product of a high-pressure ridge that has parked over the far West for much of the winter — have kept Arizona bone-dry between a freakish November rainstorm and some dustings of snow last week. Unlike the situation in California, where water rationing may force farmers to leave land fallow, Arizona’s stored water is expected to carry the state through at least another year without shortages.

“Huge difference between us and California,” said Kathleen Ferris, executive director of the Arizona Municipal Water Users Association.

Arizona has greater reservoir storage relative to its needs, and millions of acre-feet of water are socked away underground from better times on the Colorado River.

“It’s for just this kind of purpose,” Ferris said.

Despite the lack of winter rain and snow, Salt River Project’s reservoirs are about half full — the same as they were at this time last year. That’s because the reservoirs, unlike most of California’s, are built to hold multiple years’ worth of runoff and dole it out during lean times. Last year’s heavier snow, plus a strong summer monsoon and an unusual November drenching, left reservoirs in shape to weather this winter.

But Arizona forests are another story. Unless snow and rainfall pick up by spring, they will be kindling waiting for a spark, say watershed and forestry experts.

“If we don’t get some big storms to drop a snowfall that lasts awhile,” SRP’s Ester said, “the risk of catastrophic wildfire will be extreme.”

Dry conditions this century in forest and chaparral have fueled swift-moving fires that have cost Arizona dozens of homes and, last year, 19 firefighters’ lives. Since 1990, an Arizona Republic analysis found, nearly a quarter-million new homes have been built in the danger zone known as the “wildland-urban interface.”

Fires are also a serious threat to SRP, whose Salt River and Verde River watersheds pour a million acre-feet of water a year into metro Phoenix.

The U.S. Department of Agriculture’s 44 snow-measurement stations, spread out from Williams and Flagstaff in the west to Nutrioso in the east, had no measurable snow in January for the first time in at least 30 years, said Natural Resources Conservation Service water-supply specialist Dino DeSimone.

Some higher elevations, such as in the San Francisco Peaks north of Flagstaff, retained some snow from November and December storms. But many, such as the Fort Valley Experimental Forest near Flagstaff, were bare.

“It should normally have 1 or 2 feet of snow right now,” DeSimone said of Fort Valley. “It’s very unusual.”

DeSimone, a member of the State Drought Monitoring Technical Committee, said the snow-and-rainfall outlook for the rest of this winter, based on National Weather Service long-range forecasts, is poor. That means continued drying of ponderosa pines that have fed summer megafires in recent years, including the Wallow Fire of 2011, which consumed more than a half-million acres to set a state record.

“We’ve been mostly in drought for about 13 years, (and) the forests have definitely gone downhill,” DeSimone said. “A year like this only exacerbates the situation.”

Climate scientists say the upward trend in Southwestern temperatures since the late 20th century has combined with lower precipitation to intensify both drought and fires. The lack of moisture in dry years makes trees more combustible, and the added warmth increases evaporation and the trees’ need forwater. What happens in winter reverberates through summer.

“As in the Sierras, much of the vegetation in Arizona is also largely dependent on winter moisture,” said Valerie Trouet, a professor who studies forest-climate links at the University of Arizona’s Laboratory of Tree-Ring Research. “The current winter drought will result in very dry vegetation and thus increased risk of widespread fire.”

Trouet considers both the warm Western drought and the frigid Eastern “Polar Vortex” this winter to be signs of climate change. Warming in the Arctic, she said, has slowed the jet stream, locking in the regions’ respective weather patterns for unusually long periods.

The winter outlook for Colorado River flows isn’t as dire as the conditions in Arizona and most of the other places it flows past and supplies. Currently, the river-forecasting center, a branch of the National Oceanic and Atmospheric Administration, predicts a normal April-July runoff season into Lake Powell on the strength of above-average snowpack in the headwaters in the Colorado Rockies.

Still, declining water levels in the river’s major reservoirs — Lake Powell and Lake Mead — threaten to trigger a first-ever shortage for states as early as 2016. If that happens, Arizona would be the first state to lose some of its water, because California has higher-priority rights. Stored groundwater could carry the state for the foreseeable future, but state officials hope to avoid a river shortage and are in negotiations with California and other states to tweak the system.

It will be a delicate task while Californians are on high alert and some farmers there are scheduled to get no water this year because of the lack of snow in the Sierra Nevadas.

Goodyear farmer Ron Rayner said California hasn’t invested adequately in aquifer recharge or reservoirs to catch snowmelt, so two dry years in the Sierras leave farms parched — and this is the second dry year.

“They have something to learn from us,” he said.

Although he’s confident in his Arizona supply for the near future, his family also owns farmland in California’s Central Valley. Farmers who lease some of it from him may not get water this year.

Ester, of SRP, said conservation is important even if Arizona isn’t facing an imminent shortage.

“We’re well-positioned to handle another dry year,” he said. “I wouldn’t want to have another two or three after this one, but for the next year we’re in good shape.”

Posting a comment to our website allows you to join in on the conversation. Share your story and unique perspective with members of the azcentral.com community.

Comments posted via facebook:

► Join the Discussion

Join the conversation! To comment on azcentral.com, you must be logged into an active personal account on Facebook. You are responsible for your comments and abuse of this privilege will not be tolerated. We reserve the right, without warning or notification, to remove comments and block users judged to violate our Terms of Service and Rules of Engagement. Facebook comments FAQ

Join thousands of azcentral.com fans on Facebook and get the day's most popular and talked-about Valley news, sports, entertainment and more - right in your newsfeed. You'll see what others are saying about the hot topics of the day.